Over the past 25 years, the total time from baccalaureate to earning a Ph.D. in the physical sciences has risen by almost a year to 7.9 years, according to an NSF report. "Time to Degree of U.S. Research Doctorate Recipients" pulls data from 1978 to 2003 from the agency's Survey of Earned Doctorates. Among physical science fields, chemistry has the shortest time to degree, with students taking an average of 6.9 years, followed by physics . . .